Attachment means for spark electrodes



Nov. 7, 1967 w. STEUERNAGEL 3,

ATTACHMENT MEANS FOR SPARK ELECTRODES Filed April 15, 1965 2 Sheets-Sheet 1 INVENTOR Walter Stealer/wage! J ATTORNBZKS Nov. 7, 1967 w. STEUERNAGEL 3,350,850

ATTACHMENT MEANS FOR SPARK ELECTRODES Filed April 15, 1965 2 Sheets-Sheet 2 R m a N d 0 w m N r 5 1 w a Q f. F 0v P e w w W u U U /.l m

1 n "a n ATTORNEYS United States Patent 3,350,850 ATTACHMENT MEANS FOR SPARK ELECTRODES Walter Steuernagel, Frankfurt am Main, Germany, assignor to Metallgesellschaft Aktiengesellschaft, Frankfurt am Main, Germany Filed Apr. 15, 1965, Ser. No. 448,381 Claims priority, application Germany, Apr. 25, 1964, M 60,799 2 Claims. (Cl. 55--148) ABSTRACT OF THE DISCLOSURE An electrostatic filter spark electrode arrangement wherein the spark electrodes are held against thermal distortions by mounting a plurality of electrodes in a grate, securing the upper end of the grate to a frame, fastening the lower end of the grate by means of springs frictionally slidable in bores in the lower side of the frame, and hanging the frame in the electrostatic filter.

This invention relates to attachment means for spark electrodes and, in particular, to a means for holding the emitting or sparking electrodes in an electrostatic filter.

conventionally, an electrostatic filter is composed of rows of plate-like collecting electrodes between which spark electrodes are mounted on frames which are hung from insulators mounted on the roof of the filter housing. The spark electrode frames are of approximately the same size as the surfaces of the collecting electrodes. The spark electrode frames are subdivided when the height and length of the filter is extensive. To achieve eflicient dust precipitation, the voltage applied to the spark electrodes is slightly less than the voltage which would produce a short circuit as the electric field strength for producing precipitation is at its greatest power. At this applied voltage, a change in the distance between the spark electrode and the collecting electrode, that is, the spark gap, produces short circuiting called arc-over. The electric field in the filters is weakened at the arc-over points and the field breaks down entirely when a standing, that is, longlasting, arc occurs. Such impairs the efficiency of the filter. Even though the spark electrodes are carefully installed and adjusted in the erection of the filter, nevertheless, the spark electrodes will be displaced because of their weight and the warping or bending of the roof and the roof supports. Consequently, the individual spark electrodes which are secured to a supporting frame by bolts or wedges also warp so as to decrease the spark gap along parts of the frame. Warping also occurs when the raw dust-laden gas is hot because of the thermal expansion and contraction of the spark electrodes and their supporting frame. Therefore, sparks repeatedly arc-over at some points in the electrical filter which necessitates an immediate reduction in the applied voltage in order to prevent the destruction of the interior of the filter. Sometimes arcing occurs because the bent spark electrodes will be highly heated and then break causing sparking and arcing. These broken electrodes must be removed and replaced in a painstaking operation which requires the shut down of the entire filter.

The object of this invention is to produce an attachment means for the spark electrodes held in support frames in an electric filter so that the warping or bending of the spark electrodes is prevented during the thermal distortion and/or warping of the supporting frames. In this invention, the spark electrodes have their upper ends attached by bolts or wedges to the upper side of the support frame and their lower ends inserted through bores in 3,350,850 Patented Nov. 7, 1967 the lower side of the support frame and held by springs so that the spark electrodes are movable in the vertical plane of the frame. The bottom portion of each spark electrode can be composed of a round rod having two parallel grooves oppositely positioned and extending parallel to the longitudinal axis of the rod. A U-shaped. spring is seated in the grooves and serves to retain the bottom of the electrode in a bore through the lower side of the support frame. In a modified form, the spring is in the form of a split plug. In a further form, the spring is a contact spring.

According to a further feature of this invention, three or more individual spark electrodes are assembled into a grate by means of crossbars, which grate has the center of its upper side bolted to the support frame and having spring-equipped lower ends which are inserted into bores on the lower side of the support frame so that the electrodes are movable in the vertical plane of the frame. In this invention, the spark electrodes can have the shape of strap irons, angle irons or barbed wires when provided with a lower end portion in the form of a round rod and provided with spring means for securing the lower end of the electrode to the support frame.

The attachment means of this invention greatly reduces the time for assembling the electrodes in a frame and also greatly reduces the chance of a change in the spark gap. In practice, it has been found that the attachment means of this invention is very solid and rugged and is not damaged by the knocking of the support frames.

The means by which the objects of the invention are obtained are described more fully with reference to the accompanying drawings in which:

FIGURE 1 is a front elevational view of the spark electrodes held in a supporting frame in an. electric filter;

FIGURE 2 is a front view of the lower end of a spark electrode provided with a U-shaped spring;

FIGURE 3 is a crosssectional view taken on the line 3-3 of FIGURE 2;

FIGURE 4 is a front view of the lower portion of an electrode provided with a split plug spring;

FIGURE 5 is a view similar to FIGURE 4 and showing a contact spring;

FIGURE 6 is a fragmentary front view of the lower portion of an electrode inserted in a bore in the lower side of the support frame;

FIGURE 7 is a cross-sectional view on the line 7-7 of FIGURE 6;

FIGURE 8 is a perspective view of the electrode of FIGURE 6 removed from the support frame;

FIGURE 9 is a front view of electrodes assembled into a support frame or grate; and

FIGURE 10 is a front view of the grate of FIGURE 9 assembled into a support frame.

As shown in FIGURE 1, the individual spark electrodes 1 are mounted in a support frame 2. This support frame is hung by means of rods 3 from insulators 4 mounted on the filter housing roof 5. A dust collecting electrode 6 is schematically shown behind frame 2.

The upper ends of each electrode 1 are secured to the upper side 2a of frame 2 by means of bolts 1a or wedgeshaped joints. The lower ends of electrodes 1 are secured to the lower side 2b of frame 2 by a spring means such as illustrated in the various modifications of FIGURES 2 to 8. In FIGURE 2, the bottom or lower portion 7 of the round electrode 1 is provided with a pair of opposite lying grooves 8 extending longitudinally of the electrode and into which grooves is inserted a U-shaped spring 9. Bottorn portion 7, together with spring 9, is pushed through the bore in the lower frame side 212 so that electrode 1 is frictionally engaged in the bore and movable relative to the frame in the vertical plane of the frame and against the resistance of spring 9. In the modification of FIGURE 4, the spark electrode 10 is an angle iron to which a split a plug spring 11 is fastened. In the modification of FIGURE 5, a contact plate spring 12 is secured to the angle iron electrode 10. In the modification of FIGURES 6, 7 and 8, a simple plate spring 13 is interposed between the round lower end portion 7 of the electrode 10 and is pushed into the bore 13a of the lower frame side 2b.

As shown in FIGURE 9, three spark electrodes 1 which can be studded with spark points 14 are assembled into a grate by means of crossbars 15. The center of the upper crossbar 15 is joined to a bolt and nut so that the grate can be hung from the upper side 20 from the frame 2 as shown in FIGURE 10. The outermost electrodes 1 in FIGURE 9 are provided with the springs 13 for attachment to the lower side 2b of frame 2. A plurality of grates assembled into frame 2 are then ready for installation in a filter.

Having now described the means by which the objects of the invention are obtained.

I claim:

1. An electrostatic filter comprising a vertical support frame having vertically spaced apart upper and lower sides, a plurality of grates each containing at least two spark electrodes, bolt means fastening one end of each grate to the upper side of said frame, vertical bores in the lower side of said frame, and spring means attached to the lower end of at least two of said electrodes in each of said grates and frictionally engaging the inner surface of each respective bore to secure the other end of each References Cited UNITED STATES PATENTS 2,362,716 11/1944 Phillips 55-147 X 2,588,111 3/1952 Hannernan 55147 X 2,881,857 4/1959 Cosby et a1 55--147 3,016,980 1/1962 Gonzalez 55--143 X 3,073,094 1/1963 Landgraf et al. 55151 X 3,115,381 12/1963 Hoag 2473 X 3,149,937 9/1964 Revell 55--147 X FOREIGN PATENTS 738,241 10/1955 Great Britain. 855,621 12/1960 Great Britain.

OTHER REFERENCES Watson, W., A Textbook of Physics, Longman, Green & Co., 4th Ave. and 30th St., New York, N.Y., Copyright 1920, page 106.

HARRY B. THORNTON, Primary Examiner.

R. F. BURNETT, D. TALBERT, Assistant Examiners. 

1. AN ELECTOSTATIC FILTER COMPRISING A VERICAL SUPPORT FRAME HAVING VERTICALLY SPACED APART UPPER AND LOWER SIDES, A PLURALITY OF GRATES EACH CONTAINING AT LEAST TWO SPARK ELECTRODES, BOLT MEANS FASTENING ONE END OF EACH GRATE TO THE UPPER SIDE OF SAID FRAME, VERTICAL BORES IN THE LOWER SIDE OF SAID FRAME, AND SPRING MEANS ATTACHED TO THE LOWER END OF AT LEAST TWO OF SAID ELECTRODES IN EACH OF SAID GRATES AND FRICTIONALLY ENGAGING THE INNER SURFACE OF EACH RESPECTIVE BORE TO SECURE THE OTHER END OF EACH GRATE TO THE LOWER SIDE OF THE FRAME WHILE PERMITTING MOVEMENT IN A VERTICAL PLANE DURING THERMAL EXPANSION OF SAID FRAME AND ELECTRODES. 